Use PDFtoImage error in linux.

[nasterhe]

 <PackageReference Include="PDFtoImage" Version="5.0.0" />

I just added the PDFtoImage package to the project, and in Linux it won't start and throw the following exception message, how to solve it? Thanks.

Unhandled exception. System.TypeInitializationException: The type initializer for 'SkiaSharp.SKFontManager' threw an exception.
 ---> System.TypeInitializationException: The type initializer for 'SkiaSharp.SKObject' threw an exception.
 ---> System.InvalidOperationException: The version of the native libSkiaSharp library (88.1) is incompatible with this version of SkiaSharp. Supported versions of the native libSkiaSharp library are in the range [116.0, 117.0).
   at SkiaSharp.SkiaSharpVersion.CheckNativeLibraryCompatible(Version minSupported, Version current, Boolean throwIfIncompatible)
   at SkiaSharp.SkiaSharpVersion.CheckNativeLibraryCompatible(Boolean throwIfIncompatible)
   at SkiaSharp.SKObject..cctor()
   --- End of inner exception stack trace ---
   at SkiaSharp.SKObject..ctor(IntPtr handle, Boolean owns)
   at SkiaSharp.SKFontManager..ctor(IntPtr handle, Boolean owns)
   at SkiaSharp.SKFontManager.SKFontManagerStatic..ctor(IntPtr x)
   at SkiaSharp.SKFontManager..cctor()
   --- End of inner exception stack trace ---
   at SkiaSharp.SKFontManager.get_Default()
   at Avalonia.Skia.FontManagerImpl..ctor()
   at Avalonia.Skia.SkiaPlatform.Initialize(SkiaOptions options)
   at Avalonia.SkiaApplicationExtensions.<>c.<UseSkia>b__0_0()
   at Avalonia.AppBuilder.SetupUnsafe()
   at Avalonia.AppBuilder.Setup()
   at Avalonia.AppBuilder.SetupWithLifetime(IApplicationLifetime lifetime)
   at Avalonia.ClassicDesktopStyleApplicationLifetimeExtensions.StartWithClassicDesktopLifetime(AppBuilder builder, String[] args, Action`1 lifetimeBuilder)
   at TestIt.Program.Main(String[] args) in D:\Avalonia\TestIt\testit\Program.cs:line 12

[rabbitism]

It is using a SkiaSharp version that is not supported in Avalonia. Can you try some version earlier ? like 4.1

[rabbitism]

You're right, change to 4.1 and it will work, how can I update SkiaSharp if I use 5.0?

Avalonia is now providing compatibility with 3.0 preview, but PDFtoImage has already moved to 3.116 or something which is quite far away. I don't know if Avalonia team has any plan to provide such a support.

[nasterhe]

I see that the error message should be the reason for the low version of the libSkiaSharp library, I'm completely unfamiliar with Linux, let's see how I can install the new version of libSkiaSharp library.

[rabbitism]

Better ask @Gillibald for confirmation.

[stevemonaco]

You should be able to simply reference the new version in csproj. ie. <PackageReference Include="SkiaSharp" Version="3.116.1" />. Beware if you're using CPM, then you still need to PackageReference in the csproj, else you wind up with 2.88.9.

Remember to include the matching package for native assets for Linux. See #15503

[nasterhe]

The PDFToImage package already comes with SkiaSharp 3.116.1 and SkiaSharp.NativeAssets.Linux.NoDependencies 3.116.1, so there is no problem on Windows, but it is problematic on Linux.

[thevortexcloud]

If you are trying to make a PDF (rather than just convert one), I can confirm QuestPDF works fine on Linux.

https://github.com/QuestPDF/QuestPDF

[nasterhe]

yad --print --filename=/path/to/pdf.pdf --add-preview. You'll need to add yad as a dependency of your app.

Pls how to implement it with C# in avalonia, I'm a beginner in linux,thanks.

[thevortexcloud]

I have never used yad, but you should be able to just do (assuming it's installed):

Process.Start("yad", "--print --filename=file.pdf --add-preview");

If there is a proper API you can probably use that via a DllImport.

[nasterhe]

You can probably try sending the file directly to CUPS if you want to avoid the yad dependency. As CUPS is the standard Linux print service which most distros use.

https://www.cups.org/doc/options.html

But it's not something I have tried myself.

Thanks.Although I have been using C# for many years, I am a beginner to linux, so how can I achieve this feature in avalonia.

[thevortexcloud]

You can try similar code to what I said for yad. That said CUPS does have a proper C API, but you will probably need to write your own bindings for it. I personally have never used the C API though so I can't help much with it.

https://www.cups.org/doc/cupspm.html

But the Process.Start approach is the simplest to get working since it just launches an external program directly.

Another option is to find an IPP client for C# and use that instead, as CUPS does expose an IPP server.

[nasterhe]

Thanks a lot.I'll give it a try.